Cordage product



Feb. 24, ,1970 w. R. HOWARD ETAL 3,496,716

CORDAGE PRODUCT Filed Sept. 26, 1967 i SUPPLY EXTRUDER N Ev ORIENTATION 7 ZONE TWISTER '7-f E: 8 Q

QUENGH FIG. I.

FIG. 2.

INVENTORS WARREN R. HOWARD 8 HENRY A. HOOD I ATTORNEYS United States Patent 3,496,716 CORDAGE PRODUCT Warren R. Howard, Beverly, and Henry A. Hood,

Moorestown, N.J., assignors, by mesne assignments, to Wall Industries, Inc., Beverly, N.J., a corporation of Delaware Filed Sept. 26, 1967, Ser. No. 670,767 Int. Cl. D02g 3/06, 3/08; D21h 3/00 US. 'Cl. 57155 7 Claims ABSTRACT OF THE DISCLOSURE A cordage product comprises at least one folded ribbon being nontwisted along its major longitudinal axis having greater width than thickness and being folded at least once along at least one axis parallel to the longitudinal axis and at least the inner face of the ribbon having a plurality of axially extending ridges and grooves.

BACKGROUND OF THE INVENTION The conventional practice of the formation of twisted ropes from synthetic material involves numerous steps including the drawing of filaments, the twisting of the filaments into yarns, commonly referred to as threads or singles yarns, the twisting of these yarns to form what are known as piled yarns, ply yarns, or simply, plies, the formation of these plied yarns into strands, generally in volving the formation of concentric twisted layers of the plied yarn, and finally the laying, with twisting, of the strands into rope. The ropes in turn may be laid together to form cables. Variants of the foregoing are made involving, for example, the twisting of plied yarns into cords which are in turn formed into strands; or yarns may be plaited to form strands; or plaited yarns may be formed into cords, in turn plaited or braided to form strands, or strands formed of twisted yarns may be plaited to form ropes, etc.

The major difiic-ulties in the production of rope from synthetic plastic materials arise in the production and handling of the filaments as well as from certain disadvantages regarding the physical properties of the finished product which derive from the structural characteristics of the yarn subcomponents. Extrustion of the conventional 6 and 12' monofilaments is a very critical process entailing precise equipment and controls and a great amount of skill. The fabrication of these monofilaments into plied yarn is expensive and involves low productivity because of the small deniers and the high twist necessarily involved. In addition, numerous of these products suffer the disadvantage that knot-slip strength as well as other aspects of frictional properties, translational efficiency, etc., are often not sufiiciently superior to similar properties of cordage products derived from natural fibers. Several of these disadvantages have been overcome by modifying the physical characteristics of the synthetic cordage products or subcomponents. For example, the knot-slip strength of synthetic fibers have been improved by chemically and physically roughening the surface of the final product or subcomponents, e.g., filaments, and by the production of cordage products from fibrillated monofilaments or films. Similarly, the translational etficiency of these products has been improved by the above-noted physical and chemical surface roughening processes, by the utilization of filaments of preferred geometric crosssection, as well as numerous other means. It is, of course, well known that the uniformity, compactness, translational efficiency and frictional characteristics of cordage products can be modified by employing numerous varieties of twists and plaits or braids. However, it is ice equally well known that all of these procedures by which it is sought to improve the properties of cordage involve the requisites of additional fabrication steps, apparatus and skill.

It is therefore one object of this invention to provide an improved cordage product. It is another object of this invention to provide a cordage product having improved frictional characteristics. It is another object of this invention to provide cordage having increased knot-slip strength. It is yet another object of this invention to provide cordage having greatly improved translational efiiciency. It is another object of this invention to provide an improved cordage product which can be fabricated by an improved, simplified process.

SUMMARY OF THE INVENTION In accordance with one embodiment of this invention, there is provided a cordage product comprising a nontwisted integral thermoplastic ribbon having greater width than thickness. The ribbon is folded over on itself at least once along at least one axis parallel to the longitudinal axis of the ribbon which is provided on at least its inner face with a plurality of axially extending ridges and grooves.

BRIEF DESCRIPTION OF Til-IE DRAWING FIGURE 1 is a diagram illustrating the procedure in accordance with the invention;

FIGURE 2 is a fragmentary view showing a suitable opening in an extrusion die; and

FIGURE 3 is a fragmentary view showing the folding of the original extrustion into a flattened form.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Essentiall any cross-sectional configuration can be employed as long as the width of the ribbon before folding is greater than its thickness. Exemplary of cross-sections that can be employed in addition to laminar or flat ribbons are [(C),(V),(Z),(W),(L)] etc., cross-sections. These cross-sections are presently preferred in that they facilitate folding the ribbon following extrusion thereof. Obviously, however, any original cross-sectional shape which can be folded along an axis parallel to the major longitudinal axis of the ribbon can be employed within the concept of this invention.

The presence of ridges and grooves, e.g., striations, corrugations, etc., on at least the interface of the ribbon, i.e., those surfaces of the ribbon that are in face-to-face contact when the ribbon is in folded form, greatly enhance the lateral structural stability of the ribbon with the result that the desired compactness can be achieved and knot-strength is greatly enhanced. In another embodiment of this invention, the outer surfaces of the ribbon can also possess the above-noted striations or ridges with the result that knot-slip strength and surface frictional properties are further improved. The provisions of striations on the outer surface of the ribbon have also been found to greatly enhance translational efficiency of cordage products produced from a plurality of the nontwisted folded ribbons of this invention, for example, two or more of these integral non-twisted ribbons can be twisted about each other to form a cordage product having greater dimensions and strength. It is also presently preferred that the ribbons, i.e., cordage products, of this invention be produced from foamed thermoplastic materials. Although foaming is not necessary, it has been found to improve surface frictional characteristics with the result that knot-strength and translational efficiency are increased. Although any degree of foaming can be employed, it is presently preferred that when foamed ribbons are utilized that the degree of foaming be suflicient to reduce the density of the finished product by a factor of about 1.1 as compared to the particle density of the thermoplastic. The resultant foamed articles can possess either closed or open pores and can be foamed by essentially any foaming agents, the particular foaming agents not being an essential feature of this invention. Suitable foaming agents are, for example azobisformamide, carbonates, the sulfonyl semicarbazides, etc. In addition the desired foaming can be achieved by incorporating compressed gas in the molten thermoplastic while in the extruder with the result that expansion and foaming occur on emission of the thermoplastic from the extruder die.

The cross-sectional dimensions of the folded ribbons of this invention can vary considerably without substantial loss of the desirable physical properties. For example, the ribbons of this invention can have deniers within the range of from about 5,000 to about 60,000. This invention is applicable to any normally solid polymer resin, plastic, etc., that can be formed into the desired cross-sectional shapes. Materials which can be formed suitably into filaments, fibers, or ribbons useful herein and which can be oriented include polyamides, polyurethanes, polyesters, polyethers and anhydrides, and mixed polymers of such compounds, rubber hydrochloride, polyacrylonitrile, polymerizates of vinylidenechloride, styrene, vinyl chloride, vinyl acetate, and copolymers of these, as well as the polyolefins, such as polyethylene and polypropylene.

Polymers of aliphatic mono-l-olefins, such as ethylene, propylene, butene-l, and the like, make excellent filaments or ribbons for use in the invention. Polymers of aliphatic mono-l-olefins having a maximum of eight carbon atoms per molecule and no branching nearer the double bond than the 4-position provide foamed and unfoamed drawn filaments having particularly desirable properties. Homopolymers and copolymers, as well as mixtures of homopolymers and copolymers, are suitable materials for the filaments or ribbons of this invention.

The preparation of oriented foamed polyolefin extrudates, including filaments and ribbons, is described in U.S. Patent No. 3,214,234 (1965), Bottomley. A suitable method for preparing oriented ribbons and fibers is described in U.S. Patent No. 3,003,304 (1961), Rasmussen.

The filaments and ribbons used according to the invention can be oriented so as to give optimum strength to these materials for use in the ultimate cordage formed therefrom. Also, as indicated above, the polymers can be either foamed or unfoamed, and foaming is employed, ordinarily, to reduce weight and add bulk. The amount of foaming employed varies according to the polymer type and filament denier, but approximately 15-50 percent voids per strand is suitable for most applications described. herein. Foamed filaments, as is well known, have less elasticity and plastic memory than unfoamed filaments. Thus, cordage that is made from foamed filaments ordinarily display less snapback if the bundle breaks under an excursive load.

The amplitude of the ridges or striations can vary considerably, e.g., from to 80 percent of maximum thickness although it will generally be related to the thickness of the extruded ribbon. For example, the thickness at the ridges on an oriented ribbon having an extended width of inch and having a denier of about 17,000 was about mils and about half that at the thermal cross section i.e., in the valleys while another ribbon was inch wide, 27 mils at the ridges, about half as thick in the valleys and of about 27,000 denier.

The cordage products of this invention are preferably produced by extruding a ribbon having the desired crosssectional configuration, quenching the extrudate, followed by reheating to orientation temperature and orienting if desired. It is presently preferred that the ribbons of this invention be oriented due to the dramatic increase in tensile strength that results from such orientation. Draw ratios are preferably within the range of from about 2 to about 20. The unfolded ribbon can then be passed to a set of rollers which converge on the outside lateral walls of the ribbon forcing them together to produce the crease or fold desired in the finished product. These rollers are preferably heated to a temperature sufficient to heat set the fold so that the inner grooved faces of the ribbon remain in intimate contact. Heat setting temperatures will, of course, vary considerably, depending upon the material from which the ribbon is constructed. However, for most of those thermoplastics which are presently preferred within the concept of this invention the heat setting temperatures will usually be within the range of from about to about 600 F. In the alternative, the extrusion of the desired cross-sectional shape having the aforementioned ridges or striations on the desired surfaces can be followed immediately by folding or creasing by passing the ribbon between suitable rollers or by passing the ribbon through a second die which diminishes in lateral extent along its longitudinal axis, i.e., the direction of travel of the ribbon, by which means the Walls of the ribbon are forced to converge upon each other by passage through the die. In this latter method, care should be taken that the temperature of the ribbon is allowed to diminish substantially after extrusion and before introduction to the die or rollers so that cohesion of the thermoplastic to the die or welding of the inner surfaces of the ribbon are prevented.

The preferred procedure involved is diagrammed in FIGURE 1. Plastic is supplied through a passage 2 to the extruder 4 which feeds the plastic to a die 6 so that the ribbon 7 passes into a quench bath 8 containing guide rollers. From this bath the ribbon now cold but flexible is guided by rollers 10 to pass through an orientation zone 12 which is suitably heated.

The ribbon then passes between squeeze rollers 14 which may also be heated to achieve the flattening of the ribbon, which is delivered therefrom to a winder or twister indicated as 16.

The die is provided with a plate a portion of which is indicated at 18 having an opening such as 20 to provide an extruded ribbon of suitable shape, the opening specifically shown at 20 being of L-shape with the facing surfaces of corrugated form to provide the desired ribbon. FIGURE 3 shows the ribbon 22 as it approaches the rollers 14, the ribbon being provided with the corrugations indicated at 24. By the action of the rollers the ribbon is completely folded to the form indicated at 26. The same end may be achieved by causing it to pass through a die having an opening corresponding to the transition from the open to the folded condition of the ribbon.

We claim:

1. A non-twisted integral thermoplastic cordage product comprising a ribbon having greater width than thickness and being folded over at least once along at least one axis parallel to the longitudinal axis of said ribbon, at least the inner face of said folded ribbon having a plurality of axially extending ridges and grooves.

2. The article of; claim 1 wherein said folded ribbon is heat set to retain the crease of said fold.

3. The article of claim 2 having a denier Within the range of from about 5,000 to about 60,000 and being oriented along its major axis by a draw ratio within the range of from about 2 to about 20.

4. The article of claim 2 having a plurality of said creased folds.

5. A cordage product comprising a plurality of the nontwisted ribbons of claim 2 twisted about each other.

6. The article of claim 2 wherein said ribbon is foamed.

7. The article of claim 2 wherein both the inner and the outer surfaces of said ribbon have a plurality of axially extending ridges and grooves.

References Cited UNITED STATES PATENTS Alderfer 57-167 XR Lefevre.

Lefevre et a1. 57-167 XR Stratford 57140 10 6 3,194,716 7/ 196 5 Lefevre 161177 XR 3,332,228 7/1967 Chill 57155 3,340,571 9/1967 Bishop et a1. 161177 XR STANLEY N. GILREATH, Primary Examiner W. H. SCHROEDER, Assistant Examiner US. Cl. X.R. 

